As a wind power generation device, there is known a device in which a blade receives wind, a main shaft connected to the blade rotates, and the speed of the rotation of the main shaft is increased by a speed increaser to drive a power generator. This type of wind power generation device has a problem in that changes in wind speed and wind direction change the number of rotations transmitted from the blade to the power generator through the main shaft, the speed increaser and the like to thereby decrease the power generation efficiency.
Accordingly, to improve the power generation efficiency, the present applicant has already proposed a wind power generation device in which a one-way clutch is disposed between the speed increaser and the power generator (see Patent Document 1). In this wind power generation device, even if the wind speed and the like change to reduce the rotation speed of the main shaft, by disconnecting the output shaft of the speed increaser and the input shaft of the power generator by the one-way clutch, the input shaft of the power generator can continue to rotate by inertia without rapidly decreasing in speed, so that the average rotation speed of the input shaft can be increased to improve the power generation efficiency.
The above-mentioned one-way clutch is provided with, as shown in FIG. 8, an inner ring 101, an outer ring 102, a plurality of rollers (engagement elements) 103, a ring-shaped cage 104 holding these rollers 103 at predetermined intervals in the circumferential direction, and springs 105 elastically urging the rollers 103 toward one side in the circumferential direction. In the cage 104, a pair of annular portions 106 facing in the axial direction and a plurality of pillar portions 107 coupling the annular portions 106 are integrally formed and pockets 108 accommodating one roller 103 and one spring 105 are formed between the annular portions 106 and the pillar portions 107 adjoining in the circumferential direction. Moreover, the pillar portions 107 are provided with a protruding portion 109 protruding in the circumferential direction in order to support the spring 105 in the pocket 108.
However, since the pockets 108 are formed by the spaces surrounded by the annular portions 106 and the pillar portions 107 and the pillar portions 107 have a complicated shape having the protruding portion 109, such a method in which the cage 104 is manufactured by carving increases the cost, which is undesirable. Moreover, although a method is considered in which a synthetic resin material is injection-molded to integrally form the cage 104 having the above-described structure, since the cage 104 used for a power generation device is large in size, it is difficult to form such a large-size cage 104 by injection molding.
Accordingly, the present applicant has further proposed a split type in order that a cage for a one-way clutch as described above can be easily manufactured (see Patent Document 2). That is, as shown in FIG. 9, this split type cage 90 has a pair of annular portions 91 facing in the axial direction and a plurality of pillar portions 92 which are separate members from these annular portions 91, and is assembled by fitting the axial end portions of the pillar portions 92 to the annular portions 91.